Pavel K even if you try to make java.lang accessible? E.g. with what you had in that SO post,
--add-opens java.base/java.lang=ALL-UNNAMED or
--add-opens java.base/java.lang=weld.servlet.shaded .

The error is about not being able to invoke deep reflection on module containing CL which the above should be able to bypass.

BTW if you have some reproducer where this could be easily tried, feel free to link it to WELD-2619 as this is definitely one of the things we need to take into consideration.